Receivers use forward error correction code (FEC) to correct propagation errors in signal transmission. Most error-correcting codes are required to calculate the reliability of each received bit, which requires accurate noise power information.
Digital Terrestrial Multimedia Broadcast (DTMB) systems use Orthogonal Frequency Division Multiplexing (OFDM) multi-carrier modulation. OFDM systems usually use pilots defined by system to estimate the noise power. However, as there is no pilot in DTMB systems, it is difficult for the system to get accurate noise power. Therefore, it is desirable to obtain accurate noise power in DTMB systems.